In general, a hydraulic excavator as a typical example of a construction machine is composed of an automotive lower traveling structure and an upper revolving structure rotatably mounted on the lower traveling structure, and a working mechanism tiltably provided on a front side of the upper revolving structure.
Here, the hydraulic excavators include a small-sized hydraulic excavator called a mini shovel for performing a work at a small work site. This small-sized hydraulic excavator is also called a small-sized revolving-type excavator or a rear small-sized revolving-type excavator, for example, and this small-sized revolving-type excavator is formed in a compact manner so that a rear side of the upper revolving structure is substantially accommodated in a vehicle width of the lower traveling structure when the upper revolving structure is turned.
The upper revolving structure of the small-sized hydraulic excavator includes a revolving frame constituting a support structural body, an engine mounted in a laterally-placed state extending in a left-right direction on a rear side of the revolving frame, a heat exchanging device including an oil-cooler provided on the revolving frame on one side in the left-right direction of the engine and cooling hydraulic oil and a radiator for cooling the engine, a support member provided on the revolving frame in a state straddling the engine from an upper side, an operator's seat arranged on a front side of the engine and on which an operator is seated, and a housing such as a canopy provided by covering an upper part of the operator's seat and having a rear side supported by the support member and the like.
Here, the support member is composed of a housing support base provided by extending in the left-right direction above the engine and four leg parts mounted on both sides of the housing support base in the left-right direction, respectively, and having lower ends mounted on the revolving frame across the engine in a front-rear direction of the engine, respectively. These leg parts are provided at positions of front left, rear left, front right, and rear right with respect to the housing support base, respectively. As described above, the housing support base of the support member is arranged above the engine by the four leg parts and supports a rear-side part of the housing at this position (Patent Document 1).